Day Two (July 14, 2010)

[A-1] Codes and Standards

A-1-1

Summary of Guideline for Inspection and Evaluation of PWR Reactor Internal [Reactor Vessel Bottom-Mounted Instrumentation]

Tomonori SHICHIDA, Harutaka SUZUKI and Yusuke YOSHIDA (Mitsubishi Heavy Industries, LTD.)

Abstract
The damage caused by primary water stress corrosion crack (PWSCC) has been revealed in Reactor Vessel Head Penetration Nozzles with alloy 600 domestically and internationally in recent years. Bottom Mounted Instrumentation which has the same structure as Head Penetration Nozzle is also necessary to consider the occurrence of damage.

The guideline has been examined and studied to clarify the application of inspection techniques and preventive maintenance method, the approach to the evaluation for acceptance level of continuous operation and inspection frequency. The summary of this guideline is introduced in this paper.

Keywords
bottom-mounted instrumentation, PWSCC, alloy 600, preventive maintenance measure

A-1-2

Summary of Guideline for Inspection and Evaluation of PWR Reactor Internal [Class 1 component Nozzle Safe-end dissimilar metal weld]

Tomonori SHICHIDA, Moritatsu NISHIMURA, Takafumi HIRO and Harutaka SUZUKI (Mitsubishi Heavy Industries, LTD.)

Abstract
The damage caused by primary water stress corrosion crack (PWSCC) has been revealed in the Nozzle Safe-end with alloy 600 domestically and internationally in recent years.

The guideline has been examined and studied to clarify the application of inspection techniques and preventive maintenance method, the approach to the evaluation for acceptance level of continuous operation and inspection frequency. The summary of this guideline is introduced in this paper.

keywords
nozzle safe-end, PWSCC, alloy 600, preventive maintenance measure

A-1-3

Environmental Fatigue Evaluation in PLM Activities of PWR Plant

Takao NAKAMURA (Osaka University) and Shoichi MIYAMA (The Kansai Electric Power Co., INC. )

Abstract
Numbers of nuclear power plants have been operating for more than 30 years and some of them exceeding 40 years in Japan. In these ageing plants, fatigue evaluation has a significant measure in assuring the plant reliability. The environmental fatigue in light water reactors, which was first recognized in the 1980’s in Japan, has been drawing attention worldwide because it may cause remarkable effects on the life of important components.. This paper introduces a few examples of environmental fatigue evaluation, which was performed using the JSME codes as a part of PLM evaluation for Japanese PWR plant.

Keywords
Environmental Fatigue, Environmental Fatigue Life Correction Factor, Fen, JSME Codes, Modified Rate Approach Method, Plant Life Management

A-1-4

Report on Performance Demonstration for depth sizing of SCC flow in austenitic stainless steel pipes

Koichiro HIDE, Toshihiko SASAHARA, Tamotsu JIKIMOTO and Keiji WATANABE (Central Research Institute of Electric Power Industry)

Abstract
The PD Center at the Central Research Institute of Electric Power Industry (CRIEPI) commenced Performance Demonstration examinations for flaw depth sizing of austenitic stainless steel pipes in March 2006. As of April, 2010, 26 examination courses have been completed and 31 out of 43 candidates passed the examination. The average error margin of the successful applicant of the PD examination to the seventh stage was 0.17 mm, and standard deviation was 2.0 mm.

keywords
Performance Demonstration (PD), UT, depth sizing

A-1-5

Guideline on Application Process of Techniques Developed for Maintenance Activities

Koji KOYAMA (Mitsubishi Heavy Industries, LTD.), Akihiro SAKASHITA (The Tokyo Electric Power Company, Inc.), Shinro HIRANO (The Kansai Electric Power Co., INC. ) and Koji Dozaki (The Japan Atomic Power Company)

Abstract
From the engineering development to actual application of the new maintenance technique used for the maintenance activities of a nuclear reactor in operation, the JANTI Guideline, "the Guideline on the Application Process of a Maintenance Technique" was developed to clarify activities to be checked or examined in each process. In engineering development, all activities are provided to be checked or examined at each process followed further, such as standardization process. It is important to carry out share recognition for the activities which should be performed in each process in the prompt application to the actual plant system efficiently among the persons or organizations concerned.

Keywords
JANTI Guideline, Maintenance Activity, Authorization Process

A-1-6

Guideline on Underwater Laser Beam Clad Welding for Preventive Maintenance

Nobuichi SUEZONO, Yuuichi MOTORA (TOSHIBA CORPORATION), Akihiro SAKASHITA and Ryohei OKADA (The Tokyo Electric Power Company, Inc.)

Abstract
JANTI Guideline on underwater laser beam clad welding for preventive maintenance against SCC was published. This paper introduces the summary of that guideline. Underwater laser beam welding has good advantages for the repair and mitigation work for operating nuclear plants’ reactor internals. Since it does not need to drain the water from RPV, preparation before the work can be very concise, and dose rate that workers suffer can be controlled in very low level. And heat input during the welding procedure is almost 1/10 of conventional welding such as TIG welding. It is also better feature for the welding on the irradiated structures. Guideline on seal welding by ULBW was already published more than 2 years ago. For the next step, it is expected to discuss and publish the next Guideline on ULBW for the application on structural parts in near future.

Keywords
JANTI Guideline, ULBW, mitigation, SCC

A-1-7

Application of JSME Fitness-for-Service Code and JANTI Guideline for Inspection and Evaluation of Reactor Internals to Cracks found at Shroud Support of Tokai II Power Station

Koji DOZAKI, Koji YAMAMOTO, Shoji YAMAMOTO, Takeshi KATAOKA (The Japan Atomic Power Company) and Takashi ITO (Hitachi-GE Nuclear Energy, Ltd.)

Abstract
Cracks were found at shroud support of Tokai II Power Station in 24th outage. Flaw evaluation of these cracks was performed applying Codes for Nuclear Power Generation Facilities – Rules on Fitness-for-Service – (FFS Code) of Japan Society of Mechanical Engineers (JSME) and Guideline for Inspection and Evaluation of Reactor Internals of Japan Nuclear Technology Institute (JANTI). Evaluation methods and results are outlined in this report. Issues to be studied for better improvement of JSME FFS Code and JANTI Guideline will be discussed.

Keywords
Flaw Evaluation, Stress Corrosion Cracking, Shroud Support

A-1-8

The development of the guideline to prevent combustion of radiolysis gas in BWR piping

Tetsuhiko INAGAKI, Akira NISHIKAWA (CHUBU Electric Power Co., lnc.), Akihiro SAKASHITA (The Tokyo Electric Power Company, Inc.), Koji DOZAKI (The Japan Atomic Power Company), Takahiro SONE (TOSHIBA CORPRATION) and Akitaka HIDAKA (Hitachi-GE Nuclear Energy, Ltd.)

Abstract
The pipe rupture accidents due to combustion of radiolysis gas in BWR piping occurred in 2001. TENPES and JANTI got "The design guideline to prevent pipe rupture accident due to combustion of radiolysis gas in BWR piping" ready and proposed about ideal method of the piping placement design to BWR.

This report is the summary of the method to evaluate the possibility of accumulation of radiolysis gas in BWR piping which is mentioned in the guideline.

Keywords
BWR, branched piping, hydrogen, accumulation, combustion, detonation, design guideline

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